[MacGuffin]

It sounds like you have some kind of gut feeling that to you, this behavior might not be acceptable to you or your boyfriend. When people feel that hesitancy, and therefore need to look elsewhere to validate their behavior, then it's a sign they probably shouldn't be doing it. In other words, when in doubt, refrain from it. Another way to look at it is put yourself in your significant other's shoes. If you found out your boyfriend were sexing it up with other girls in chat rooms, would you be happy and okay with it? Something is telling me you probably wouldn't be.

Talk to your boyfriend about this, before you go on a chat again. Hiding it is only going to lead to problems. See if their is anything you can do to make your living situation something both parties can be okay with and get their needs met with, because I think that is the real issue.